Prostate cancer is the most common type of cancer found in American men, other than skin cancer. According to American Cancer Society, there will be about 234,460 new cases of prostate cancer in the United States in 2006 and about 27,350 men will die of this disease. Prostate cancer is only curable at an early stage. Therefore, early detection is extremely important to reduce mortality and enhance the cure rate.
Current screening for prostate cancer relies on digital rectal examination and prostate specific antigen (PSA) value measurement. And definitive diagnosis of prostate cancer is based on histological tissue analysis. This is most often obtained via needle biopsy, guided by transrectal ultrasound (TRUS). Currently biopsy is the only way to confirm the diagnosis of the prostate cancer. During a biopsy an urologist obtains tissue samples from the prostate. A biopsy gun inserts the needle into the prostate and removes the tissue sample in less a second. However, in TRUS-directed biopsies, tissue sampling within different sections is done in a random fashion, since no prior information about the spatial location of the cancer is available. Normally, urologists divide the left and the right parts of the prostate into 3 regions each and randomly sample each of them. This not only causes pain to the patient (55% of men report discomfort during prostate biopsy), but also decreases the accuracy of the method (this method has shown to have a large false negative detection rate ranging from 27% to 39%).